source: trunk/source/processes/electromagnetic/lowenergy/src/G4hBetheBlochModel.cc @ 1315

Last change on this file since 1315 was 819, checked in by garnier, 16 years ago

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25//
26//
27// -------------------------------------------------------------------
28//
29// GEANT4 Class file
30//
31//
32// File name:     G4hBetheBlochModel
33//
34// Author:        V.Ivanchenko (Vladimir.Ivanchenko@cern.ch)
35//
36// Creation date: 20 July 2000
37//
38// Modifications:
39// 20/07/2000  V.Ivanchenko First implementation
40// 03/10/2000  V.Ivanchenko clean up accoding to CodeWizard
41//
42// Class Description:
43//
44// Bethe-Bloch ionisation model
45//
46// Class Description: End
47//
48// -------------------------------------------------------------------
49//
50//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
51
52#include "G4hBetheBlochModel.hh"
53#include "G4DynamicParticle.hh"
54#include "G4ParticleDefinition.hh"
55#include "G4Material.hh"
56#include "globals.hh"
57
58//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
59
60G4hBetheBlochModel::G4hBetheBlochModel(const G4String& name)
61  : G4VLowEnergyModel(name), 
62    lowEnergyLimit(1.*MeV),
63    highEnergyLimit(100.*GeV),
64    twoln10(2.*std::log(10.)),
65    bg2lim(0.0169), 
66    taulim(8.4146e-3)
67{;}
68
69//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
70
71G4hBetheBlochModel::~G4hBetheBlochModel() 
72{;}
73
74//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
75
76G4double G4hBetheBlochModel::TheValue(const G4DynamicParticle* particle,
77                                      const G4Material* material) 
78{
79  G4double energy = particle->GetKineticEnergy() ;
80  G4double particleMass = particle->GetMass() ;
81
82  G4double eloss  = BetheBlochFormula(material,energy,particleMass) ;
83
84  return eloss ;
85}
86
87//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
88
89G4double G4hBetheBlochModel::TheValue(const G4ParticleDefinition* aParticle,
90                                      const G4Material* material,
91                                      G4double kineticEnergy) 
92{
93  G4double particleMass = aParticle->GetPDGMass() ;
94  G4double eloss  = BetheBlochFormula(material,kineticEnergy,particleMass) ;
95
96  return eloss ;
97}
98
99//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
100
101G4double G4hBetheBlochModel::HighEnergyLimit(
102                             const G4ParticleDefinition* ,
103                             const G4Material* ) const
104{
105  return highEnergyLimit ;
106}
107
108//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
109
110G4double G4hBetheBlochModel::LowEnergyLimit(
111                             const G4ParticleDefinition* aParticle,
112                             const G4Material* material) const
113{
114  G4double taul = (material->GetIonisation()->GetTaul())*
115                  (aParticle->GetPDGMass()) ;
116  return taul ;
117}
118
119//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
120
121G4double G4hBetheBlochModel::HighEnergyLimit(
122                             const G4ParticleDefinition* ) const
123{
124  return highEnergyLimit ;
125}
126
127//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
128
129G4double G4hBetheBlochModel::LowEnergyLimit(
130                             const G4ParticleDefinition* ) const
131{
132  return lowEnergyLimit ;
133}
134
135//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
136 
137G4bool G4hBetheBlochModel::IsInCharge(const G4DynamicParticle* ,
138                                      const G4Material* ) const
139{
140  return true ;
141}
142
143//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
144 
145G4bool G4hBetheBlochModel::IsInCharge(const G4ParticleDefinition* ,
146                                      const G4Material* ) const
147{
148  return true ;
149}
150
151//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
152
153G4double G4hBetheBlochModel::BetheBlochFormula(
154                             const G4Material* material,
155                                   G4double kineticEnergy,
156                                   G4double particleMass) const
157{
158  // This member function is applied normally to proton/antiproton
159  G4double ionloss ;
160
161  G4double rateMass = electron_mass_c2/particleMass ;
162
163  G4double taul = material->GetIonisation()->GetTaul() ;
164  G4double tau  = kineticEnergy/particleMass ;    // tau is relative energy
165 
166  // It is not normal case for this function
167  // for low energy parametrisation have to be applied
168  if ( tau < taul ) tau = taul ; 
169   
170  // some local variables
171   
172  G4double gamma,bg2,beta2,tmax,x,delta,sh ;
173  G4double electronDensity = material->GetElectronDensity();
174  G4double eexc  = material->GetIonisation()->GetMeanExcitationEnergy();
175  G4double eexc2 = eexc*eexc ;
176  G4double cden  = material->GetIonisation()->GetCdensity();
177  G4double mden  = material->GetIonisation()->GetMdensity();
178  G4double aden  = material->GetIonisation()->GetAdensity();
179  G4double x0den = material->GetIonisation()->GetX0density();
180  G4double x1den = material->GetIonisation()->GetX1density();
181  G4double* shellCorrectionVector =
182            material->GetIonisation()->GetShellCorrectionVector();
183   
184  gamma = tau + 1.0 ;
185  bg2 = tau*(tau+2.0) ;
186  beta2 = bg2/(gamma*gamma) ;
187  tmax = 2.*electron_mass_c2*bg2/(1.+2.*gamma*rateMass+rateMass*rateMass) ;
188       
189  ionloss = std::log(2.0*electron_mass_c2*bg2*tmax/eexc2)-2.0*beta2 ;
190   
191  // density correction     
192  x = std::log(bg2)/twoln10 ;
193  if ( x < x0den ) {
194    delta = 0.0 ;
195
196  } else { 
197    delta = twoln10*x - cden ;
198    if ( x < x1den ) delta += aden*std::pow((x1den-x),mden) ;
199  }
200   
201  // shell correction
202  sh = 0.0 ;     
203  x  = 1.0 ;
204
205  if ( bg2 > bg2lim ) {
206    for (G4int k=0; k<=2; k++) {
207        x *= bg2 ;
208        sh += shellCorrectionVector[k]/x;
209    }
210
211  } else {
212    for (G4int k=0; k<=2; k++) {
213        x *= bg2lim ;
214        sh += shellCorrectionVector[k]/x;
215    }
216    sh *= std::log(tau/taul)/std::log(taulim/taul) ;     
217  }
218   
219  // now compute the total ionization loss
220   
221  ionloss -= delta + sh ;
222  ionloss *= twopi_mc2_rcl2*electronDensity/beta2 ;
223
224  if ( ionloss < 0.0) ionloss = 0.0 ;
225 
226  return ionloss;
227}
228
229
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